Non-explosive energetic material and a reactive armor element using same

ABSTRACT

The present invention provides elements for making a protective reactive armor to be fitted on the outside of an enclosure liable to be exposed to attack by shaped-charge warheads and other threats, such as kinetic energy projectiles and fragments, to thereby enhance survivability of the enclosure and its contents. The invention further provides a non-explosive energetic material useful for such reactive armor elements

FIELD OF THE INVENTION

The present invention is concerned with elements for making a protective reactive armor to be fitted on the outside of an enclosure liable to be exposed to attack by shaped-charge warheads and other threats, such as kinetic energy projectiles and fragments, to thereby enhance survivability of the enclosure and its contents. The invention is further concerned with a non-explosive energetic material useful for such reactive armor elements.

Examples of enclosures protectable by a reactive armor element made of elements according to the invention are land vehicles such as battle tanks, armored personnel carriers, armored fighting vehicles, helicopters, armored self-propelled guns; armored static structures such as buildings, above-ground portions of bunkers, container tanks for the storage of fuel and chemicals; etc.

BACKGROUND OF THE INVENTION

Warheads with shaped-charge munitions, also known as hollow charge munition, are known to pierce armors and thereby destroy the protected object from within and, its contents. This capacity of a shaped charge results from the fact that upon detonation there forms an energy-rich jet also known as “thorn” or “spike” which advances at very high speed of several thousands of meters per second and is thereby capable of piercing even relatively thick armor walls.

Several arrangements have become available in recent years to afford protection against the penetrating effect of an exploding shaped charge, wherein a structure holding at least one reactive armor element, wherein reactive armor element comprises an array of layers comprising one or more plate layers and at least one layer of explosive or any other energetic material (‘energetic material’—a material releasing energy during activation/excitement), tightly bearing against at least one of the plate layers. The plate layers are made, for example, of metal or a composite material.

A basic reactive armor element comprises two metal plates sandwiching between them the layer of energetic material. Such prior art reactive armor elements are based on the mass and energy consuming effects of moving plates and their functioning is conditional on the existence of an acute angle between the jet of an oncoming hollow charge threat and the armor itself.

In general, a reactive armor element is a multi-layer body in which each layer tightly bears against each contiguous layer, wherein the multi-layer body includes an outer cover plate, at least one layer of energetic material, at least one intermediary inert body juxtaposed to each of the at least one energetic material layer. Upon activation/excitement of the energetic material (e.g. upon striking by shaped-charge warhead) the jet energizes the armor, where a vast energy discharge occurs so that within microseconds the discharged gases accelerate the metal plates and displaces them away from one another thus disrupting/defeating the jet, thereby loosing its energy to penetrate the protected enclosure.

Whilst efficiency and survivability of the armor are important, the overall performance of an armor is determined by comparing its efficiency versus its survivability. One criteria of an armor, having significant importance, is the ratio of weight per area unit of the armor element. An other criteria of importance is sensitivity of the energetic material. Whilst sensitivity may be an advantage for improving efficiency of the armor, it may reduce survivability of the armor and it may be problematic as far as complying with various transportation requirements.

There are known four principal groups of intermediate materials for armors, disclosed hereinafter in order of their energetic catachrestic:

A. Explosive Reactive Armor (ERA):

Explosive Reactive Armor is the most effective technology to defeat hollow charges, kinetic projectiles, small arms, shrapnel etc. Advanced ERA concepts are considered leap-ahead technology against emerging anti-armor threats. The major challenges of applying ERA to ground combat vehicles are the use of an explosive material as an intermediate layer of the sandwich element, reducing survivability of the armor.

B. Self-Limiting Explosive Reactive Armor (SLERA):

Self-Limiting ERA provides reasonable performance, substantially better than NERA (see below), though less than ERA, with reduced effects on vehicle structures, as compared to ERA. The energetic material layer in SLERA has the potential of being classified as a passive material (NATO specification). SLERA can provide good multiple-hit capability in modular configuration. Thus, while the energetic material used in SLERA is not as effective as fully detonable explosives, this type of reactive armor may provide a more practical option than ERA owing to its survivability characteristics.

C. Non-Explosive Reactive Armor (NxRA):

Non-Explosive Reactive Armor provides a comparable efficiency to SLERA, comparable survivability to NERA (see below), and excellent multiple-hit capability against hollow charge warheads. NxRA's advantages over other reactive armor technologies are that it is totally passive and has substantially better efficiency than NERA.Energetic materials for NxRA are disclosed for example in DE 3132008C1 and in U.S. Pat. No. 4,881,448.

D. Non-Energetic Reactive Armor (NERA):

Non-Energetic Reactive Armor has limited efficiency against hollow charges. NERA's advantage is that it is totally passive and thus provides excellent survivability and maximal multiple-hit capability, comparable to NxRA.

It is an object of the present invention to provide a non-explosive energetic material suitable for NxRA which does not contain explosive material and fulfills its protective function (high efficiency and high survivability of the armor), whilst the non-explosive energetic material lowers the requirements of transportation and logistics according to various standards e.g. UN regulations as appearing in the Recommendations on the Transport of Dangerous Goods.

It is a further object of the present invention to provide an armor element fitted for such an energetic material and where the armor is of comparable efficiency to SLERA and of comparable survivability to NERA.

SUMMARY OF THE INVENTION

The above and other objects are achieved by using a non-explosive energetic material being a gas generator, comprising oxidizers and fuels, whereby exciting the material upon striking by a jet of a hollow charge results in vast generation of gas which accelerates/bulges the armor plates of the reactive armor. This however requires that the gas be discharged rapidly, i.e. not more than a few μsec (microseconds), to thereby ensure disruption/defeating of the jet, and to minimize the penetration into the protected environment.

For that purpose, a group of oxidizers was selected and a group of fuels, which together with suitable catalyst/s and binder/s provide the resultant non-explosive energetic material to constitute a gas generator. According to one particular embodiment, the non-explosive energetic material comprises an oxidizer selected from the group of families comprising, among others, nitrates, nitrites, chromates, dichromates, perchlorates, chlorates, etc. and fuels of any type of carbon containing material, and a suitable binder which may also serve as a fuel.

According to one particular embodiment, the non-explosive energetic material comprises sodium nitrate (NaNO₃) as an oxidizer and a silicone binder as a fuel. It is also possible to combine several types of oxidizers and fuels so as to improve performance of the energetic material in the reactive armor element.

An example for a catalyst material suitable for use with the non-explosive energetic material in accordance with the present invention is a transition metal oxide, such as Fe₂O₃ (ferric oxide), which is usually used as a catalyst in energetic materials based on combinations of oxidizers and fuels.

In order to increase the reaction rate of the non-explosive energetic material, micro-balloons (i.e. hollow sphere elements) may be added to the formulation. It is appreciated that the micro-balloons increase the reaction rate upon striking of the armor by a jet of a hollow charge.

Accordingly, such a composition may be considered as a non-explosive material (, i.e. a non-class 1 material, as per definitions of the UN Regulations and the US Department Of Transportation (DOT).

The non-explosive energetic material according to the present invention may be a flexible sheet of material, pliable and it is easily cut, pierced, etc. whereby it is conveniently applied between the bearing plates of the armor element. According to one particular embodiment the material is rubber-like and is easily foldable.

According to the present invention there is provided a NxRA element with a non-explosive energetic material of the above type for protection against shaped-charge warheads, as well as against small arms, shrapnel, fragments and various types of kinetic projectiles, e.g. Armor Piercing Fin Stabilized Discarded Sabot (APFSDS).

The NxRA element comprises a module fitted with an outer cover plate and at least one sandwich element within the module. Said sandwich element comprising at least one pair of substantially flat inert plates with a non-explosive energetic material as disclosed herein above applied there between.

According to some embodiments, there may be several pairs of inert plates, e.g. made of metals (such as steel, aluminum, titanium), ceramics, composite materials and others, where the non-explosive energetic material is applied there between. Furthermore, the cover plate of the casing of the reactive armor, may constitute a front plate (or a top/bottom plate) of the at least one sandwich element.

A reactive armor according to the present invention may be of any shape and size as known in the art, suited for applying to different enclosures, and may be of various configurations.

A reactive element according to the invention (NxRA) is efficient against shaped charge war-heads, giving as an example RPG7, as well as against various types of kinetic projectiles, e.g. APFSDS, small arms (e.g. 14.5 mm), shrapnel and fragments. A NxRA element according to the present invention provides comparable efficiency to SLERA as discussed hereinabove, as well as comparable survivability to NERA. The NxRA element is advantageous over other reactive armor technologies as it is totally passive, as NERA, and it offers improved survivability to the protected enclosure, to neighbouring reactive elements and further provides excellent multiple-hit capability against hollow-charge warheads, small arms and kinetic projectiles and eliminates fragmentation hazards.

DETAILED DESCRIPTION OF THE INVENTION

According to the present invention there is provided a non-explosive energetic material being a gas generator, comprising oxidizers and fuels, whereby exciting the material upon striking by a jet of a hollow charge results in vast generation of gas which accelerates/bulges the armor plates of the reactive armor.

This however requires that the gas be discharged rapidly, i.e. not more than a few μsec (microseconds), to thereby ensure disruption/defeating of the jet, and to minimize the penetration into a protected environment.

For that purpose, a group of oxidizers is selected and a group of fuels, which together with suitable catalyst/s and binder/s to provide the resultant non-explosive energetic material to constitute a gas generator.

According to one particular embodiment, the non-explosive energetic material comprises an oxidizer selected from the group of families comprising, among others, nitrates, nitrites, chromates, dichromates, perchlorates, chlorates, etc. and fuels of any type of carbon containing material, and a binder which may also serve as a fuel.

According to one particular embodiment, the non-explosive energetic material comprises sodium nitrate (NaNO₃) as an oxidizer and a silicone binder as a fuel. It is also possible to combine several types of oxidizers and fuels so as to improve performance of the energetic material in the reactive armor element.

An example for a catalyst material suitable for use with the non-explosive energetic material in accordance with the present invention is a transition metal oxide, such as Fe₂O₃ (ferric oxide), which is usually used as a catalyst in energetic materials based on combinations of oxides and fuels.

In order to increase the reaction rate of the non-explosive energetic material, micro-balloons (i.e. hollow spheric elements) may be added to the formulation. It is appreciated that the micro-balloons increase the reaction rate upon striking of the armor by a jet of a hollow charge.

Such spheric elements may be made for example of glass, plastic material, metallic or ceramic materials. The diameter of such spheres may be about 40 μm, though other dimensions may be also suitable.

The non-explosive energetic material according to the present invention is a flexible sheet of material, pliable and it is easily cut, pierced, etc. whereby it is conveniently applied between the bearing plates of the armor element. According to one particular embodiment the material is rubber-like and is easily foldable.

The energetic material qualifies as a non-class 1 material as defined by UN Regulations and the US Department Of Transportation (DOT), and is thus a non-explosive energetic material.

The non-explosive energetic material is suitable for manufacturing a NxRA element for protection of enclosures against shaped-charge warheads, small arms, shrapnel, fragments and kinetic projectiles. Such a reactive armor element comprises a casing attached to the enclosure and fitted with an outer cover plate, and at least one sandwich element extending behind the plate; said sandwich element comprising at least one pair of substantially flat plates with the non-explosive energetic material applied there between.

It is appreciated that the above descriptions are intended only to serve as examples and that many other embodiments are possible, all of which fall within the spirit and the scope of the present invention. 

1. A reactive armor element for protection against various types of threats, comprising a casing fitted with an outer cover plate, and at least one sandwich element extending behind the plate; said sandwich element comprising at least one pair of substantially flat plates with an energetic material applied there between, wherein said energetic material is a non-explosive material comprising an oxidizer and a fuel agent, which together with a suitable catalyst material and a binder provide the resultant non-explosive energetic material, constitute a gas generator
 2. A reactive armor according to claim 1, wherein the oxidizer is selected from a group of families comprising nitrates, nitrites chromates, dichromates, perchlorates and chlorates.
 3. A reactive armor according to claim 2, wherein the energetic material comprises sodium nitrate (NaNO₃) as an oxidizer.
 4. A reactive armor according to claim 1, wherein the catalytic material is a transition metal oxide.
 5. A reactive armor according to claim 4, wherein the catalyst material is Fe₂O₃.
 6. A reactive armor according to claim 1, wherein the energetic material comprises a binder serving as a fuel.
 7. A reactive armor according to claim 6, wherein the binder is a silicone binder.
 8. A reactive armor according to claim 1, wherein the energetic material comprises hollow micro-balloons for increasing reaction rate thereof.
 9. A reactive armor according to claim 8, wherein the hollow micro-spheres have a diameter of about 40 μm.
 10. A reactive armor according to claim 8, wherein the hollow micro-spheres are made of a material selected from the group of materials comprising, among others, glass, plastic material, metallic and ceramic materials.
 11. A reactive armor according to claim 1, wherein the energetic material is in the form of a flexible and pliable sheet of material.
 12. A reactive armor according to claim 1, wherein the energetic material is a non-class 1 (non-explosive) material.
 13. A reactive armor element according to claim 1, wherein the energetic material has uniform thickness and density.
 14. A reactive armor element according to claim 1, wherein the plates are made of inert material.
 15. A reactive armor element according to claim 1, wherein the plates are made of metal or ceramics or composite material.
 16. A reactive armor element according to claim 1, comprising a plurality of sandwich elements disposed within the casing.
 17. A reactive armor element according to claim 1, wherein the cover plate of the casing constitutes a front plate of the at least one sandwich element.
 18. A reactive armor element according to claim 1, being an add-on armor type.
 19. A sandwich element for a reactive armor, comprising at least one pair of substantially flat plates with a non-explosive energetic material applied between said at least one pair of plates, wherein said energetic material is a non-explosive material comprising an oxidizer and a fuel agent, which together with a catalyst material and a binder provide the resultant non-explosive energetic material, constituting a gas generator.
 20. A sandwich element according to claim 19, wherein the energetic material is in tight surface contact with the plates.
 21. A sandwich element according to claim 19, wherein the oxidizer is selected from a group of families comprising nitrates, nitrites chromates, dichromates, perchlorates and chlorates.
 22. A sandwich element according to claim 21, wherein the energetic material comprises sodium nitrate (NaNO₃) as an oxidizer.
 23. A sandwich element according to claim 19, wherein the energetic material comprises binder serving as a fuel.
 24. A sandwich element according to claim 23, wherein the binder is a silicone binder.
 25. A sandwich element according to claim 19, wherein the energetic material comprises catalyst material is a transition metal oxide.
 26. A sandwich element according to claim 19, wherein the catalyst material is Fe₂O₃.
 27. A sandwich element according to claim 19, wherein the energetic material is a non-class 1 (non-explosive) material.
 28. A sandwich element according to claim 19, wherein the energetic material comprises hollow micro-balloons for increasing reaction rate thereof.
 29. A sandwich element according to claim 28, wherein the hollow micro-balloons have a diameter of about 40 μm.
 30. A sandwich element according to claim 28, wherein the hollow micro-balloons are made of a material selected from the group of materials comprising, among others, glass, plastic material, metallic and ceramic materials.
 31. A sandwich element according to claim 19, wherein the energetic material is in the form of a flexible and pliable sheet of material.
 32. An energetic material for a reactive armor, characterized in that said material is a non-explosive energetic material comprising an oxidizer and a fuel agent, which together with a catalyst material and a binder provide the resultant non-explosive energetic material, constituting a gas generator.
 33. An energetic material according to claim 32, wherein the oxidizer is selected from a group of families comprising nitrates, nitrites chromates, dichromates, perchlorates and chlorates.
 34. An energetic material according to claim 33, wherein the energetic material comprises sodium nitrate (NaNO₃) as an oxidizer.
 35. An energetic material according to claim 32, wherein the catalytic material is a transition metal oxide.
 36. An energetic material according to claim 35, wherein the catalyst material is Fe₂O₃.
 37. An energetic material according to claim 32, wherein the energetic material comprises a binder serving as a fuel.
 38. An energetic material according to claim 37, wherein the binder is a silicone binder.
 39. An energetic material according to claim 32, wherein the energetic material comprises hollow micro-balloons for increasing reaction rate thereof.
 40. An energetic material according to claim 39, wherein the hollow micro-balloons have a diameter of about 40 μm.
 41. An energetic material according to claim 39, wherein the hollow micro-balloons are made of a material selected from the group of materials comprising, among others, glass, plastic material, metallic and ceramic materials.
 42. An energetic material according to claim 32, wherein the material is in the form of a flexible and pliable sheet of material.
 43. An energetic material according to claim 32, being a non-class 1(non-explosive) material.
 44. An energetic material according to claim 32, wherein the energetic material has uniform thickness and density.
 45. A method of protecting an enclosure against various types of threats, comprising the step of: fitting the enclosure on an outside with a reactive armor element comprising a casing fitted with an outer cover plate, and at least one sandwich element extending behind the plate; said sandwich element comprising at least one pair of substantially flat plates with energetic material applied between said at least one pair, said energetic material is a non-explosive material comprising an oxidizer and a fuel agent, which together with a suitable catalyst material and a binder provide the resultant non-explosive energetic material, constitute a gas generator.
 46. A method according to claim 46, wherein the energetic material is a non-class 1 (non-explosive) material.
 47. A method according to claim 46, wherein the oxidizer is selected from a group of families comprising nitrates, nitrites chromates, dichromates, perchlorates and chlorates.
 48. A method according to claim 46, wherein the energetic material comprises sodium nitrate (NaNO₃) as an oxidizer.
 49. A method according to claim 46, wherein the catalytic material is a transition metal oxide.
 50. A method according to claim 49, wherein the catalyst material is Fe₂O₃.
 51. A method according to claim 46, wherein the energetic material comprises a binder serving as a fuel.
 52. A method according to claim 51, wherein the binder is a silicone binder. A method according to claim 46, wherein the energetic material comprises hollow micro-balloons for increasing reaction rate thereof.
 53. A method according to claim 52, wherein the hollow micro-balloons have a diameter of about 40 μm.
 54. A method according to claim 52, wherein the hollow micro-balloons are made of a material selected from the group of materials comprising, among others, glass, plastic material, metallic and ceramic materials.
 55. A method according to claim 46, wherein the material is in the form of a flexible and pliable sheet of material.
 56. A method according to claim 46, wherein the energetic material has uniform thickness and density. 